Piston for aerosol dispensers



March 18, 1969 VELLEKOOP 3,433,134

PISTON FOR AEROSOL DISPENSERS Filed NOV. 22, 1967 mvmvrozz. PETER BARRIE VELLE KOOP ATTORNEY United States Patent 6 Claims ABSTRACT OF THE DISCLOSURE A piston for use in an aerosol can having an outer tubular container provided with a propellant gas therein. The piston has a cylinder provided with a centrally concave wall together with a centrally disposed disk. A plurality of supports join the cylinder and the disk and are equally spaced at an angle of approximately fortyfive degrees to each other. The wall supports are arranged in vertically aligned pairs and extend along the disk substntially one-half the radius thereof. The cylinder has upper and lower wiping edges defined by the concave wall and the entire piston assembly may be integrally molded from a synthetic plastic material.

This invention relates to an aerosol dispenser construction, and more particularly to a piston adapted to be used in an aerosol dispenser.

Various types of pistons have been devised for use in aerosol-type dispensers such as disclosed in the patent to Featherstone et al., No. 3,312,378, issued Apr. 4, 1967, for Dispensing Containers. Aerosol dispensers have heretofore generally utilized pistons formed of metal. These metal pistons in order to function properly must be light in weight and thus they are generally stamped of light gauge sheet metal. The use of sheet metal in aerosol cans, while in some cases may be desirable, in other cases may impart a flavor or odor to the contents of the dispenser and are far more expensive and difllcult to produce when compared to the cost and ease of manufacture of pistons out of a synthetic plastic material. Because of the structural limitations of construction by way of metal stampings, the wiping edges of the pistons have generally been too close to each other for optimum operation so that a satisfactory seal for the propellant gas is not always obtainable.

The present invention overcomes the disadvantages of the prior art piston constructions for aerosol dispensers by utilizing a piston which maybe formed of a synthetic plastic material and which is so arranged that its upper and lower peripheral wiping edges are spaced well apart and the piston is provided with means for preventing buckling of the piston and collapse of the wiper flanges as might have occurred in failures of previous piston constructions.

The invention features the use of wall supports for preventing the collapse of the wiper flanges as well as a central disk for maintaining the concave shape of the cylinder wall of the piston.

An object of the invention is to prevent fluid seepage from either side of the piston which is important because in an aerosol dispenser there is gas on both sides of the piston. The construction of this invention features an arrangement of parts including a cylinder of synthetic plastic material provided with slightly concave walls providing for two peripheral wiper flanges widely spaced from each other. The concave shape of the wall of the cylinder is maintained by a central disk. A plurality of vertically aligned pairs of wall supports are fastened to both the wall and the disk to give rigidity, prevent buckling, and to limit expansion and contraction of the 3,433,134 Patented Mar. 18, 1969 cylinder wall. The wall supports are of substantially the same thickness as the disk and of greater thickness than the wall and extend along the disk substantially one-half the radius of the disk while terminating just short of the upper and lower inner edges of the cylinder wall.

Still further objects and features of this invention reside in the provision of a piston for an aerosol dispenser that is simple in construction, capable of being easily produced, inexpensive to manufacture, and which is efficient in operation for preventing gas seepage.

These, together with the various ancillary objects and features of this invention, which will become apparent as the following description proceeds, are attained by this piston for aerosol dispensers, a preferred embodiment of which is illustrated in the accompanying drawing, by way of example only, wherein:

FIG. 1 is a partial longitudinal sectional view through an aerosol dispenser showing the construction of the piston in detail; and

FIG. 2 is a sectional detail view taken along the plane of line 2-2 in FIG. 1, illustrating in particular the arrangement of parts of the wall supports used in the invention.

With continuing reference to the accompanying drawing, wherein like reference numerals designate similar parts throughout the various views, reference numeral 10 generally designated an aerosol dispenser employing the novel piston generally indicated by reference numeral 12 in its construction. The aerosol dispenser 10 includes an outer container or can 14 which is provided with a propellant gas. The propellant gas is disposed in the space 20 below the piston 12 and is for pushing the piston 12 upwardly and is also provided to push the material to be dispensed outwardly through a conventional aerosol valve head. The material to be dispensed is disposed in the space 22 above the piston 12.

The piston 12 comprises a cylinder 24 having a centrally concave wall 26. It is to be particuarly noted that the center 28 of the wall 26 is the most inwardly disposed portion thereof and the taper of the wall 26 defines two similar peripheral wiper edges 30 and 32 for engaging the inner surface 34 of the sleeve, thereby preventing gas seepage in either direction above or below the piston 12. Preferably integrally formed with the wall 26 is a central disk 36 which extends across the cylinder 24 at the center 28 thereof and is of substantially greater thickness than the wall 26. The concave shape of the wall 26 is maintained by the disk 36 which is perpendicularly disposed with respect to the wall 26.

Eight pairs of wall supports 38 and 40 are provided for giving rigidity to the piston construction and to prevent buckling while also limiting expansion and contraction of the wall 26. These Wall supports 38 and 40 are of substantially the same thickness as the disk 36 and are preferably integrally fastened to the disk 36 and to the side wall 26. The wall supports 38 and 40 are vertically superimposed above each other in alignment with each other and extend angularly at forty-five degrees relative to each other. The wall supports 38 and 40 extend along the disk 36 far enough to prevent buckling as for example onehalf of the radius thereof, as shown in the drawing, while also terminating just short of the inner peripheral edges 42 and 44 of the side wall 26. The sides 46 and 48 of the wall supports 38, 40 that extend inwardly toward the center of the piston are convex in shape, thus further rigidifying the entire construction.

In use, because the wiper edges 30 and 32 are widely spaced from each other, the piston is stable Within the sleeve 16 and the possibility of gas seepage is substantially eliminated. Further, the wall supports prevents buckling and failure of the wiper seals while the disk 36 maintains the shape of the piston.

I claim:

1. A piston for an aerosol container which comprises: a cylinder having a centrally concave Wall defining upper and lower peripheral outer wiping edges and upper and lower inner peripheral edges; a disk centrally disposed in said cylinder; and a plurality of unconnected supports connected to said cylinder and said disk, each of said supports extending radially from said cylinder inwardly along a portion of said disk and extending along a portion of said cylinder wall, said supports extending upwardly and downwardly from said disk and being efiective to impart rigidity, prevent buckling and limit expansion and contraction of said cylinder.

2. A piston according to claim 1 wherein said supports terminate on said wall just short of said upper and lower inner peripheral edges.

3. A piston according to claim 1, wherein said cylinder, said disk, and said supports are integrally molded with each other of a synthetic plastic material.

4. A piston according to claim 1, wherein said supports are arranged in vertically aligned pairs above and below said disk.

5. A piston for an aerosol container which comprises: a cylinder having a centrally concave wall defining upper and lower peripheral outer wiping edges and upper and lower inner peripheral edges; a disk centrally disposed in said cylinder; and a plurality of unconnected wall supports joined to said disk and said wall and being arranged in vertically aligned pairs above and below said disk, each of said wall supports extending along said disk substantially one-half the radius of said disk, being of substantially the same thickness as said disk and extending along said wall just short of said upper and lower inner peripheral edges, said wall supports being effective to prevent buckling and to limit expansion and contraction of said cylinder.

6. A piston according to claim 5, wherein said wall supports are equally spaced from each other and disposed at an angle of forty-five degrees to each other.

References Cited UNITED STATES PATENTS 1,575,080 3/1926 Rundell 92-l94 1,796,415 3/ 1931 Tyler 92-194 2,754,164 7/ 1956 Schwarz 92245 2,887,347 5/1959 Losey 92241 2,995,451 8/1961 Leach. 3,132,570. 5/ 1964 Hoifman et a1. 92-245 3,176,595 4/1965 Schwantz 92243 3,207,385 .9/ 1965 Featherstone et a1. 222389 FOREIGN PATENTS 427,988 5/ 1935 Great Britain.

SAMUEL F. COLEMAN, Primary Examiner.

US. 01. X.R. 

